Influence of crystal orientation on microstructure and mechanical properties and its control for nickel-base single crystal superalloys

Nickel-based single superalloys are important materials for blades in aero-engines and land based gas turbine for its excellent high temperature strength. It has been established that nickel-base superalloys preferentially grow along <001> orientation. This paper summarizes the influence of crystal orientation on the mechanical properties of nickel-based single crystal superalloys castings. The tensile properties, creep life and low cycle fatigue (LCF) are depend on crystal orientation. Single crystals with <001> orientations have optimized high temperature mechanical properties. Based on the author's research features in the field, dendrites in the longitudinal section for the crystals with <011> orientation showed "V" and "W" patterns, while the primary dendrites in the transverse section aligned in lines. Meanwhile, the dendrite arm spacings and microsegregation of elements along different orientations are obviously different. The main function of starter block of spiral grain selector is to optimize the crystal orientation, and the spiral part is to ensure that only one grain can be obtained. Furthermore, we include some influencing factors related to the misorientation and the crystal growth for the seeding technology. Finally, we discussed the possible development trends of the crystal orientation in future.